1. Field of the Invention
The present invention relates to a noise reduction apparatus, a noise reduction method, and a noise reduction program, and more particularly, to a noise reduction apparatus, a noise reduction method, and a noise reduction program that suppress a sudden sound in an environment in which a sudden sound is periodically included in a voice signal.
2. Description of Related Art
When a mobile communication device is used in a noise environment, noise reduction processing may be required to secure the intelligibility of a voice. In particular, in an apparatus like a radio device that is frequently used in a harsh environment, a continuous periodic sudden sound like a vibration sound of an oxygen tank or a ground compressor in a construction site may overlap with a voice, which interrupts accurate transfer of the voice. Japanese Unexamined Patent Application Publication Nos. 2002-251823 and 2011-205598 disclose techniques related to noise reduction.
Japanese Unexamined Patent Application Publication No. 2002-251823 discloses a method of reducing a noise generated from a movable lens unit of a camera-integrated VTR, a noise generated when a head contacts a magnetic tape or the head is detached from the magnetic tape, a sound of an optical shutter in the camera-integrated VTR having a silver salt film camera function, and sudden sound at the time of the head seek that occurs during a recording in a rotary storage medium. Specifically, in Japanese Unexamined Patent Application Publication No. 2002-251823, signals are cut off only during a sudden sound section and information omitted during a cut-off section is interpolated based on signal information either before the cut-off section or after the cut-off section.
In Japanese Unexamined Patent Application Publication No. 2011-205598, an envelope line of a signal including a sudden noise is calculated, a signal corresponding to signal components of the sudden noise is extracted, and the signal components of the sudden noise are reduced based on the signal components of the sudden noise that are extracted.